The Stress Finite Element Analysis of Die-Holes in Biomass Flat Die Briquetting Process

摘要

Biomass briquetting technology is one of the key technologies in the utilization of biomass energy. In this paper, the mechanical characteristics of the die holes were analyzed to set up mathematical model in the briquettes forming process. The effects of the three key structure parameters, which include the inlet angle, forming taper angle and length-diameter ratio, were carried out by using the finite element software. The results indicated that the die hole with forming taper is easy to form back pressure, and the higher taper angle, the greater equivalent stress value is found in the corresponding parts, which is helpful for forming process. Combined with processing cost, energy consumption and wear analysis, the die hole forming taper should not be too big. For the corn straw, it can satisfy the molding pressure requirements to take 2° forming taper. The parameter of inlet angle main influences material grabbing, production efficiency and flat die manufacturing cost. For the corn straw, the inlet angle between 40° and 50° of die hole is not only beneficial to material grabbing and forming, but also can control flat die manufacturing cost and guarantee a certain production efficiency. Length to diameter ratio main influences the stress distribution in shape-preserving section and reflects the compressed extent of the material. Combined with energy consumption analysis, length to diameter ratio between 4:1 and 5:1 can guarantee the corn straw forming requirements. The above numerical simulation method and results can provide some reference for the flat die structure design and parameter optimization.